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* Remove __napi_schedule_irqoff?
@ 2020-10-17 13:45 Heiner Kallweit
  2020-10-17 23:29 ` Jakub Kicinski
  0 siblings, 1 reply; 12+ messages in thread
From: Heiner Kallweit @ 2020-10-17 13:45 UTC (permalink / raw)
  To: Eric Dumazet, Eric Dumazet, David Miller, Jakub Kicinski; +Cc: netdev

When __napi_schedule_irqoff was added with bc9ad166e38a
("net: introduce napi_schedule_irqoff()") the commit message stated:
"Many NIC drivers can use it from their hard IRQ handler instead of
generic variant."
It turned out that this most of the time isn't safe in certain
configurations:
- if CONFIG_PREEMPT_RT is set
- if command line parameter threadirqs is set

Having said that drivers are being switched back to __napi_schedule(),
see e.g. patch in [0] and related discussion. I thought about a
__napi_schedule version checking dynamically whether interrupts are
disabled. But checking e.g. variable force_irqthreads also comes at
a cost, so that we may not see a benefit compared to calling
local_irq_save/local_irq_restore.

If more or less all users have to switch back, then the question is
whether we should remove __napi_schedule_irqoff.
Instead of touching all users we could make  __napi_schedule_irqoff
an alias for __napi_schedule for now.

[0] https://lkml.org/lkml/2020/10/8/706

^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2020-10-23 19:22 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-17 13:45 Remove __napi_schedule_irqoff? Heiner Kallweit
2020-10-17 23:29 ` Jakub Kicinski
2020-10-18  8:02   ` Eric Dumazet
2020-10-18  8:20     ` Heiner Kallweit
2020-10-18 17:19       ` Jakub Kicinski
2020-10-18 17:57         ` Heiner Kallweit
2020-10-18 18:02           ` Jakub Kicinski
2020-10-19 10:33         ` Thomas Gleixner
2020-10-19 17:55           ` Jakub Kicinski
2020-10-23 19:21       ` Grygorii Strashko
2020-10-18  9:55   ` Thomas Gleixner
2020-10-18 11:57     ` Heiner Kallweit

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